Stir-Frying and Sweating

Two important variations on frying exploit opposite ends of the temperature scale. One is high-temperature stir-frying. The vegetables are cut into pieces sufficiently small that they heat through in about a minute, and they’re cooked on a smoking-hot metal surface with just enough oil to lubricate them, and with constant stirring to ensure even heating and prevent burning. In stir-frying it’s important to preheat the pan alone and add the oil just a few seconds before the vegetables; otherwise the high heat will damage the oil and make it unpalatable, viscous, and sticky. The rapidity of stir-frying makes it a good method for retaining pigments and nutrients. At the other extreme is a technique sometimes called “sweating” (Italian soffrito or Catalan soffregit, both meaning “underfrying”): the very slow cooking over low heat of finely chopped vegetables coated with oil, to develop a flavor base for a dish featuring other ingredients. Often the cook wants to avoid browning, or to minimize it; here the low heat and oil function to soften the vegetables, develop and concentrate their flavors, and blend those flavors together. Vegetables cooked in a version of the confit are immersed in oil and slowly cooked to soften them and infuse them with the oil’s flavor and richness.